Local Exchange Carriers (LECs) within the telecommunication industry have implemented a variety of digital transmission systems to service their customers. As diagrammatically illustrated in FIG. 1, a typical digital transmission system may contain a first (network or central office site-associated) transceiver unit 10 that is coupled to a first (e.g., central office) end 21 of a single twisted pair of telephone wires (or span) 20, and a second (remote site-associated) transceiver unit 30 coupled to a remote end 22 of the twisted pair 20. Also, the central office transceiver unit 10 may be equipped to supply electrical power over twisted pair 20 to remote transceiver 30.
In such a ‘span-powered’ configuration, it is often desirable for multiple central office transceiver units to derive span power for their respective remote transceiver units from a common or shared electrical power source. When a system incorporates span-powering of multiple remote units from a common electrical power source, there is the possibility that any individually span-powered twisted pair telephone line may incur an insulation failure—resulting in an electrical current path to earth. This electrical current path to earth is known as a ‘ground fault’ and a person's body can serve as this path. A ground faulted telephone line can present a hazardous voltage condition to service personnel and can interrupt normal power source operation, which results in transceiver malfunction on all of the connected twisted pair telephone lines.
Hazardous voltage, power source interruption and resulting multiple transceiver malfunction are unacceptable network conditions. If the particular twisted pair telephone line that is ground-faulted can be identified, then that particular line can be isolated from the power source and the remaining multiple span-powered twisted pair telephone lines and associated transceivers can continue normal operation and the hazardous voltage can be isolated.